My shepherd had these exact symptomos. After being misdiagnosed as pemphigus and given a cure that nearly killed her, we concluded that it was a stubborn case of lip fold pyoderma.

If your dog responds to antibiotics ( preferably Clavamox ) then it is very likely lip fold pyoderma. Lip fold pyoderma is stubborn and my shepherd is on her 4th antibiotic regiment. The first three regiments were not long enough to rid it completely and it came back after about a week. The last regiment has been Clavamox twice a day full strength for your dog's weight for two months, then a very gradual weaning off of Clavamox for another few months. Currently she is on half-dosage of the orginal prescribed amount.

If your dog responds to antibiotics ( after 4-5 days ) then assume that it is very likely lip fold pyoderma and not something more serious. It might be stubborn so go thru the entire antibiotic regiment which might have to be for an extended period. My dog's symptoms (itching lips ) returned after being off antibitics for 3 days. I quickly resumed a longer course of the antibiotics as discussed.

Don't let your dog be misdiagnosed. Lip fold pyoderma is common and often misdiagnosed as pemphigus.